Electron discharge tube and electrode therefor



Oct. 28, 1958 F. J. PILAS 2,858,469

ELECTRON DISCHARGE TUBE AND ELECTRODE THEREFOR Filed June 27, 1955 United States Patent ELECTRON DISCHARGE TUBE AND ELECTRODE THEREFOR Frank J. Pilas, Lyndhurst, N. J., assignor to Radio Corpo- Y This invention relates to electron tubes and particularly to a new and improved electrode and electrode assembly therefor.

Electron tubes comprise, in general, a plurality of electrodes including a centrally disposed tubular cathode and an open-ended tubular anode surrounding the cathode and with one or more grid electrodes interposed between the cathode and anode. Ordinarily, flat mica plates having appropriate slots or holes therein are secured to opposite ends of the electrodes for holding them in the desired spaced-apart relationship.

One known type of anode includes thin metal ears or tabs extending beyond the open ends thereof and adapted to be inserted into appropriate slots in the mica plates. These tabs are generally crimped or bent over to secure them to the mica. This type of anode construction creates problems in the mass production manufacture of electron tubes and particularly in the automatic assembly of the electrode elements thereof. For example, when such anodes are fed from a reservoir to a mounting position, they are generally disposed one above another in a feed chute with the ears or tabs in contact. 'Any slight displacement of the anodes causes the ears to slide past each other in face-to-face relationship and the anodes become wedged together. Thus, it is often difiicult to separate the anodes to allow them to be fed one at a time to the mounting position and quite often the separation cannot be achieved without damaging the anode.

In addition, the above-described crimping operation used to secure the anode to the mica plates represents an undesired additional step in the assembly procedure. Morevore, a thin projecting ear or tab is relatively weak and generally cannot be manipulated to form a strong and rigid union with the mica plates with the result that such an electrode assembly is often subject to undesirable microphonics in operation. Another undesirable feature of an electrode assembly including such an anode results from the fact that in welding electrode leads or tube support rods to the anode, the assembled electrodes must be turned to present the flat face of each anode tab to the welding machine. Thus a separate turning operation is required for each welding operation and for each tab.

Accordingly, one object of this invention is to provide an improved electron tube and electrode assembly therefor.

Another object of the invention is to provide an improved electrode assembly for an electron tube which, by reason of its economy of parts, is comparatively easy to assemble and requires a minimum number of operations.

Still another object of the invention is to provide an improved anode construction for electron tubes which lends itself readily to mass production methods and to the automatic assembly of the electrodes of electron tubes.

A further object of the invention is to provide an improved anode electrode which is adapted for automatic assembly with other electrodes and which lends itself to the formation of a strong and rigid assembly of electrodes.

In general, the principles and objects of the invention are achieved in an electron tube which contains an electrode assembly including at least a cathode and an anode surrounding the cathode. A pair of insulating plates are secured to opposite ends of the cathode and anode to support them and to secure them in the desired spacedapart relationship. According to the invention, the anode is provided with a plurality of projecting flanges or cars at each end which comprise a plurality of members angularly disposed with respect to each other and having terminal portions which lie in substantially the same plane. Thus, the flanges or ears may be generally T-shaped or the like and are adapted to be locked in similarly shaped slots in the insulating plates.

The invention is described in greater detail in connection with the accompanying sheets of drawings wherein:

Fig. 1 is an elevational view, partly in section, of an electron tube embodying the principles of the invention;

Fig. 2 is an exploded view in perspective of some of the components of the tube shown in Fig. 1;

Fig. 3 is a perspective view of a modification of a portion of the anode electrode shown in Fig. 2;

Fig. 4 is an exploded view in perspective of a bi-part anode constructed in accordance with the principles of the invention; and,

Fig. 5 is an elevational view of portions of two anodes as they appear in automatic assembly apparatus.

The invention is described with reference to a pentode tube it) which, referring to Figs. 1 and 2, includes upper and lower insulating plates 12 and 14, respectively, of mica or the like, which are provided for retaining the various electrode components of the tube and supporting them in the correct relationships. The electrodes employed in a pentode tube also include an indirectly heated cathode 16 adapted to be secured at its ends within central apertures 18 in the mica plates; a control grid 20 which is dimensioned to surround the cathode and is provided with side rods 22, the ends of which are adapted to be inserted into pairs of openings 24 in the mica plates; a screen grid 26 which is dimensioned to surround the cathode and control grid and is provided with side rods 28, the ends of which are adapted to be inserted into pairs of openings 30 in the mica plates; and a suppressor grid 32 dimensioned to surround the cathode and control and screen grids and is provided with side rods 34, the ends of which are adapted to be inserted into openings 36 in the mica plates; and a tubular anode 38 dimensioned to surround the aforementioned electrodes and adapted to be secured within T-shaped openings 40 in the mica plates. 7

According to the invention, the anode 38 includes an open-ended, tubular, metallic main body portion 42 having a plurality of flanges or tabs 44, preferably diametrically oppositely disposed, extending beyond the open ends thereof. Preferably, two flanges are provided at each 'end of the anode. The flanges 44 comprise a plurality of plates, for example two plates 46 and 47, disposed at an angle with respect to each other. The plates 46 and 47 are preferably planar and terminate beyond the ends of the main body portions in flat end surfaces 46 and 47 which lie in substantially the same plane. In one suitable arrangement shown in Figure 1, the plates 46 and 47 are disposed perpendicular to each other so that the flanges 44 are T-shaped in cross-section. The plates 46 may comprise extensions of the main body portion 42 and the plates 47 may comprise radial pro- Patented Oct. 28, 1958.

end surface 47' of. each flange is adjacent. to thesurface 46' of the-.plate 46 and substantially coplanar. therewith.

A portion247 tapers downwardly toa planar portion 347 which lies in a plane substantially parallel to.the plane of the surfaces 46 and 47 The surface 347 provides a seat for themica spacer and the taperedv portion promotes the insertion of the flanges into the openings in the mica spacers.

The fianges44 and the slots 40 in the mica plates 12 and 14 are dimensioned to provide aforce fitbetween at least one corresponding part of..each whereby a strong and rigid electrode assembly is achieved. Thus, for example in..one flange construction, the plate 4% is thinner than the corresponding portion of the slot 46 adapted to receive itwhile the plate 47 is slightly thicker than the correspondingportion of the slot ill-adapted to receive it.

After the various electrodes have been assembled as described above, the assembly is secured to a conven tional tube base 48 (Fig 1) which carries a plurality of contact pins 49 and a plurality of electrical leads and support members for contact to each of the electrodes. Referring to Fig. 1, leads 50 are welded to the'cathode heater wire 52, a lead. 54 is welded to a side rod 22 of the control grid, a lead 56 is welded to a side rod 28 of the screen grid, a lead 58 is welded to a side rod 34 of the suppressorgrid, and a lead 60 is connected between the cathode 16 and a side rod 34 of the suppressor grid. In addition, leads or rods 62 are welded to the two lower ears44 of the anode 38. An evacuated glass envelope 64 is provided surrounding the electrodes of the tube and secured to the base 48.

Referring to Fig. 4 in one construction, an anode embodying the principles of the invention is of bi-part construction and consists of two semicircular members 66 and 66 having L-shaped flanges 70 and 70, respectively, extending along the edges and beyond the ends thereof. The L-shaped flanges are secured together, back-to-back, for example by welding, to form the T-shaped flanges.

One advantage of the anode construction described herein may be appreciated from a consideration of Fig. 5 which shows portions of two anodes 38 and 38 positioned one above the other in a feed chute 71 as they are directed to the anode mounting position. It can be seen thatthe lower T-shaped flanges 44 of the anode 38 rest on the upper T-shaped flanges 44' of the anode 38' and, it is. clear, that even with considerable relative movement of the anodes with respect to each other, one or another portion of the lower flanges 44 will prevent the upper flanges from slipping past them to cause wedgingof the flanges. Thus a space 72 is provided between adjacent anodes and a guide arm (not shown) may be inserted into the space without striking either anode .to hold the upper anode 38 and allow the lower anode 38 to drop into mounting position.

Another advantage of the invention appears from a 4 consideration of Fig. 1 wherein it can be seen that when it is desired to weld the various leads and support rods to the various electrodes, the assembly may be positioned as shown and all of the welds may be made in order without shifting the assembly. This advantage accrues to the present invention because of the T-shaped anode flanges which present the plates 47 in the proper orientation for welding of the rods 62 thereto.

What is claimed is:

1. An electrode for use in an electron tube comprising an open ended generally tubular member having elongated projecting portions extending beyond an open end of said member and spaced across said open end, said projecting portions being generally T-shaped in crosssection throughout their length and terminating in coplanar end surfaces normal to the longitudinal dimension of said projecting portions, said end surfaces describing a planar area larger than the sum of the areas of said end surfaces, whereby said projecting portions of saidelectrode are adapted to engage similar projecting por-- tions of another similar electrode during tandem feed thereof with freedom from wedging.

2. An electrode for use in an electron discharge tube comprising an open-ended generally tubular member, a

' pair of substantially diametrically opposed flanges extending along the length of said body and having elongated projecting ears extending beyond each end of said body, said projecting ears of said flanges comprising two flat portions extending laterally of said ears and angularly disposed with respect to each other and having two angularly disposed elongated end surfaces describing a planar area normal to the longitudinal dimension of said ears and of larger magnitude than the sum of the areas of said end surfaces, whereby said electrode is preserved from wedging with another similar electrode when fed in endwise tandem relation with said similar electrode, and said flat angularly disposed portions of said ears effectively restrain relative movement between said ears and supports for said electrode.

3. An electrode for use in an electron discharge tube comprising a pair of similar members each having a.-

generally semicircular cross-section, each of said members having a pair of oppositely disposed edges, a flange extending along each of said opposed edges of each of said members with projecting portions thereof extend-- ing beyond the ends of said members and terminatingin a common plane, said portions being generally Lshaped,;- corresponding flanges of said members being 'secured together along their lengths to form a single generally tubular member with the projecting portions of said-'- corresponding flanges comprising a composite projection having a generally T-shaped cross section.

References Cited in the file of this patent 

